System for monitoring air quality and docking station for a mobile robot equipped with air quality sensors

ABSTRACT

The invention relates to a system for monitoring air quality in an environment, including at least one mobile robot (20) in the environment, a docking station (10) placed in the environment and including a parking area for receiving the robot, air quality sensors on board the mobile robot, air quality sensors fitted in the docking station, and a calibration manager for collecting measures carried out by at least one air quality sensor on board the mobile robot (20) while the mobile robot is received in the parking area of the docking station (10), and measures carried out at the same time by another air quality sensor fitted in the docking station, of the same type as the on-board air quality sensor.

The present invention relates to a system comprising one or more mobilerobots and one or more associated docking stations.

BACKGROUND

Service robotics is a growing field. Mobile robots can be dedicated tovarious functions such as floor cleaning (for example US 2006/190133A1), transporting loads (for example WO 2013/119942 A1), patrollingwarehouses (for example FR 2,987,689 A1), monitoring air quality inclosed environments (for example WO 2015/063119 A1), etc.

Mobile robots are associated with docking stations. The primary role ofthe docking stations is to provide energy. This is generally electricpower, the robot being equipped with a battery that is recharged when itdocks with the station. Usually each robot has its own docking stationwhere it is parked when not carrying out its tasks, its rechargingoccurring during that time.

The docking station has a charge management system that tracks thecharge of the robot from start to full recharge.

The docking station often has a robot guidance feature, allowing therobot to reach the proper position in the station to begin charging.Various devices exist for such guidance. The most common are based on asystem of infrared light emitting diodes (LED) enabling the robot todetermine the direction to take from its position relative to thedocking station. For example, see US 2015/0057800 A1 concerning adocking station for a robot vacuum cleaner.

Sometimes there is also a physical docking guidance system at thestation. Such a physical guidance system, however, poses problems whichrestrict the design of the robot/docking station pair.

More generally, it seems desirable to improve robustness in guiding therobot to the correct position relative to the docking station, in otherwords to improve the success rate of the procedure of positioning therobot at the station.

Existing docking stations usually only offer to docked mobile robots anenergy recharging service, although robots may have other requirementsdepending on the services they provide.

Service robotics are enabling the introduction of new types of robotsinto the workplace and the home. These have different shapes, sizes, andrequirements for energy and continuity of supply. These emergingrequirements and the need to integrate large groups of robots thatpotentially recharge on the same station generally have not beenconsidered in the design of existing docking stations. This hindersgrowth in service robotics and in the multitude of services that canresult from new relationships between the station and robots ofdifferent capabilities.

To facilitate deployment of mobile robot fleets at a given site, thedesign of the docking station should enable it to accommodate differentrobots, including robots of different sizes. Deployment will also befacilitated if the same robot can engage with different dockingstations.

Another aspect to consider is the safety of the charge managementprocedures. EP 1841038 A2 describes a charging station having a safetyfeature to prevent short circuits when a metal object touches its chargecontactors. This type of measure may be insufficient, however. If robotsof different types are likely to be accepted by the same station, chargefeatures suitable for each of them must be offered, while ensuring thatthe charging process takes place under acceptable physical conditionsand preventing the station from supplying electric power in the absenceof an authorized and identified robot.

An object of the present invention is to address at least some of theabove needs.

SUMMARY

A docking station for a mobile robot is proposed, comprising:

-   -   a robot parking area;    -   sources of attracting beams arranged around the parking area in        order to emit attracting    -   beams within a robot approach region; and    -   sources of repelling beams arranged on either side of the        parking area in order to emit, outside the approach region,        repelling beams of shorter range than the attracting beams.

These arrangements ensure that the robot can approach the station fromthe appropriate directions, defined by the attracting beams, whileavoiding collisions with the station due to approaching frominappropriate directions defined by the repelling beams. Typically, theattracting beams are emitted in front of the station, while therepelling beams are emitted laterally.

In one embodiment, the sources of attracting beams are arranged suchthat the attracting beams are emitted in directions which intersect at afixed point of the parking area. One of the sources of attracting beamsmay be arranged to emit an attracting beam having priority feature, sothat a mobile robot executes a final path between the fixed point and adocking position in the parking area. This method ensures accuratepositioning of the robot docked in the docking station without the needfor mechanical guidance means.

In one particular configuration of the docking station, the sources ofattracting beams are arranged to emit an attracting beam in a firstdirection and two attracting beams in two respective directions whichare symmetrically oriented with respect to the first direction. Sourcesof repelling beams are arranged on each side of the parking area inorder to emit two attracting beams outside of the approach region in tworespective directions which are symmetrically oriented with respect tothe first direction.

The repelling beams, which are shorter-range than the attracting beams,may have a wider beamwidth than the attracting beams. Guidance toward aspecific direction is achieved by attracting beams which are relativelynarrow, while the directions of approach to be avoided are marked bywider repelling beams.

One embodiment of the docking station further comprises:

-   -   a beam source activation controller for activating the beam        sources alternately according to an activation time cycle; and    -   a beacon signal source for emitting a beacon signal around the        docking station, indicating a current phase of the activation        time cycle.

The activation time cycle may comprise a step of emitting repellingbeams and, for each source of attracting beams, a step of emitting theattracting beam from said source. Detection of the beacon signal by arobot approaching the docking station allows it to identify which beamit is currently receiving (attracting or repelling). It can then decidewhich maneuver to make in order to come and connect to the dockingstation.

The activation time cycle may also comprise a step of no beam emissionduring which the ambient noise is measured. From this measurement, theinfrared signal detection criteria can be adjusted to reflect thesignal-to-noise ratio, which is variable. This allows determining ifwhat the infrared sensors are detecting corresponds to a useful signalor to ambient noise to be ignored.

In one embodiment, the beacon signal further indicates an identifier ofthe docking station. By decoding the beacon signal, a mobile robot canthen ensure that it is approaching a docking station appearing in a listof authorized stations that it has stored.

When the docking station provides the basic function of recharging amobile robot, it comprises a pair of contactors typically arranged inthe parking area. It may further comprise a communication interface forcommunicating with a mobile robot docked in the parking area, controlledto transmit a mobile robot identification request in response to voltagedetected at the contactors. The communication interface with the mobilerobot, when there is no contact, generally also operates while the robotis approaching and has not yet docked in the docking station.

Advantageously, a recharging controller is configured to provide chargepower to the contactors if a mobile robot identifier authorized for thestation is received via the communication interface, after a request foridentification is transmitted.

A docking station according to the invention may further be equippedwith a wireless communication access point for mobile robots, and anetwork interface for transmitting data obtained by the mobile robots toa data collection server.

The network interface may be configured to retrieve updated files forthe embedded software of the mobile robots, the updated files beingtransmitted to the mobile robots via the wireless communication accesspoint. The station itself can be updated by this process.

Independently of the above features or in combination therewith, asystem is proposed for monitoring air quality in at least oneenvironment, comprising:

-   -   at least one mobile robot in the environment;    -   a docking station placed in the environment and having a parking        area for receiving the robot;    -   air quality sensors on board the mobile robot;    -   air quality sensors installed in the docking station; and    -   a calibration controller for collecting measurements made by at        least a first air quality sensor on board the mobile robot,        while the mobile robot is docked in the parking area of the        docking station, and for collecting measurements made at the        same time by a second air quality sensor installed in the        docking station and of the same type as said first air quality        sensor.

This system makes use of the time the robots must spend in the dockingstations, usually for recharging, to verify the measurements made, forthe same air surrounding the docking station, by the sensors on boardthe robots and those permanently installed in the docking station. Thisconsiderably reduces the maintenance operations required to verifyproper calibration of the sensors.

The calibration controller of the system can be configured to transmitto the mobile robot drift observed in the collected measurementscorrection parameters.

This calibration controller may be more or less remote. However, it iswise to install it at least in part in the docking station, with anotherpart in the robots. The system may then further comprise a collectionserver communicating with the calibration controller to process thecollected measurements and provide drift observed in the collectedmeasurements correction parameters. The collection server can thendetermine the drift correction parameters in order to calibrate thefirst air quality sensor on board the mobile robot, relative to thesecond air quality sensor installed in the docking station. When thedocking station is able to successively receive a plurality of mobilerobots in the parking area, the collection server may be configured toprocess measurements made by first air quality sensors of the same typeon board their respective mobile robots while said mobile robots aresuccessively received in the parking area, in comparison to measurementsmade at the same time by the second air quality sensor installed in thedocking station and of the same type as said first air quality sensors.Another interesting possibility is for the processing of measurements bythe collection server to include an analysis of the differences observedbetween the measurements made by the first air quality sensors and thosemade at the same time by the second air quality sensor, and triggeringan alert when the analyzed differences meet a predefined alertcondition. When the system has multiple docking stations, the collectionserver is advantageously configured to communicate with calibrationcontrollers installed at least in part in a plurality of dockingstations.

According to another aspect, a mobile robot docking station comprises:

-   -   a parking area for receiving at least one mobile robot in an        environment where the docking station is placed;    -   reference sensors of the same type as the air quality sensors on        board a mobile robot; and    -   a calibration controller to collect air quality measurements        made by at least one air quality sensor on board a mobile robot        while said mobile robot is received in the parking area, and        measurements made at the same time by a reference sensor of the        docking station.

The docking station may further comprise a network interface fortransmitting data obtained by the mobile robot to a collection server,the calibration controller being configured to transmit to thecollection server, via the network interface, the air qualitymeasurements made by the air quality sensor on board the mobile robotwhile said mobile robot is received in the parking area, and themeasurements made at the same time by a reference sensor of the dockingstation. The calibration controller may be configured to transmit to themobile robot drift observed in the collected measurements correctionparameters.

Independently of the foregoing features, or in combination therewith, amethod is proposed for recharging the battery of a mobile robot in anenvironment, using a docking station located in the environment. Themethod comprises:

-   -   moving the mobile robot to the docking station;    -   emitting a wireless beacon signal from the docking station;    -   upon detection of the beacon signal by the mobile robot, the        mobile robot communicates with the docking station such that the        docking station retrieves information concerning the mobile        robot; and    -   initiating the recharging of the battery of the mobile robot in        a manner that is dependent on the retrieved information        concerning the mobile robot.

Establishing an exchange of information between the docking station andthe newly arrived robot allows a secure process for charging the robot,and/or for adapting the characteristics to the type of robot inquestion. The method thus allows managing the charging of a robot fleethaving different characteristics or identities, using one or moredocking stations.

In one embodiment of the method, the information retrieved by thedocking station concerning the mobile robot comprises an identifier ofthe mobile robot, the charging beginning if the mobile robot identifierincluded in the retrieved information corresponds to an identifier in alist of authorized robots stored in the docking station.

In particular, the charge power can be selected based on the informationretrieved by the docking station concerning the mobile robot.

One advantageous embodiment of the recharging method comprises:

-   -   in response to detection of the beacon signal by the mobile        robot, presenting a voltage at an electric power receiving        interface comprised in the mobile robot for recharging the        battery, for example a pair of charge terminals accessible from        outside the robot;    -   in response to detection of the voltage at an electric power        delivery interface comprised in the docking station, for example        a pair of contactors accessible from outside the station,        transmitting an identification request from the docking station        to the mobile robot; and    -   transmitting information concerning the mobile robot to the        docking station in response to the identification request.

Typically, the beacon signal carries an identifier of the dockingstation. One can then ensure that the mobile robot is prevented fromtransmitting information concerning the mobile robot when the dockingstation identifier received in the detected beacon signal does not matchany identifier in a list of authorized docking stations stored in themobile robot.

While recharging the battery of the mobile robot, the method maycomprise:

-   -   monitoring parameters such as at least the battery voltage of        the mobile robot, the charge current delivered to the mobile        robot, and the temperature of a charging circuit of the docking        station; and    -   stopping the charge power when the recharging conditions are no        longer met.

In another aspect, the robotic equipment comprises:

-   -   at least one mobile robot, the mobile robot comprising:        -   a battery;        -   a motor system powered by the battery to move the mobile            robot within an environment;        -   an electric power receiving interface for recharging the            battery; and        -   a first communication interface; and    -   at least one docking station to be placed in the environment,        the docking station comprising:        -   a parking area for receiving at least one mobile robot;        -   a source of electric power;        -   an electric power delivery interface for cooperating with            the electric power receiving interface of a mobile robot            received in the parking area and charging the battery of            said mobile robot from the source of electric power;        -   a source of wireless beacon signal for transmitting a beacon            signal around the docking station;        -   a second communication interface for cooperating with the            first communication interface of the mobile robot and            retrieving information concerning the mobile robot received            in the parking area after emission of the beacon signal by            the source of the beacon signal; and        -   a recharging controller for recharging the battery of the            mobile robot received in the parking area in a manner that            is dependent on the information concerning the mobile robot            received via the second communication interface.

In another aspect, a mobile robot docking station comprises:

-   -   a parking area for receiving at least one mobile robot in an        environment where the docking station is placed;    -   a source of electric power;    -   an electric power delivery interface coupled to the source of        electric power in order to recharge a battery of a mobile robot        received in the parking area;    -   a source of wireless beacon signal for transmitting a beacon        signal around the docking station;    -   a communication interface for communicating with the mobile        robot received in the parking area in order to retrieve        information concerning said mobile robot after transmission of        the beacon signal by the source of the beacon signal; and    -   a recharging controller for recharging the battery of the mobile        robot received in the parking area in a manner that is dependent        on the information concerning said mobile robot retrieved via        the communication interface.

According to another aspect, a mobile robot comprises:

-   -   a battery;    -   a motor system powered by the battery to move the mobile robot        within an environment;    -   an electric power receiving interface for recharging the        battery, the power coming from a docking station located in the        environment;    -   a wireless beacon signal detector for detecting a beacon from        the docking station;    -   an interface for communicating with the docking station; and    -   a controller configured to:        -   in response to detection of the beacon signal, present a            voltage at the electric power receiving interface; and        -   in response to receiving an identification request via the            interface for communicating with the docking station after            presenting a voltage to the electric power receiving            interface, transmitting identification information            concerning the mobile robot to the docking station.

When the beacon signal carries an identifier of the docking station, thecontroller can be configured not to transmit the mobile robotidentification information when the docking station identifier receivedin the detected beacon signal does not match any identifier in a list ofauthorized docking stations stored in the mobile robot.

BRIEF DESCRIPTION OF DRAWINGS

Other features and advantages of the invention will be apparent from thefollowing description of an exemplary non-limiting embodiment, withreference to the accompanying drawings in which:

FIG. 1 is a diagram of an exemplary docking station having features ofthe invention, in plan view;

FIG. 2 is a perspective diagram of the docking station of FIG. 1, with amobile robot docked;

FIG. 3 is a block diagram of units which are part of a docking stationin an exemplary architecture suitable for implementing the invention;

FIG. 4 is a block diagram of units which are part of a mobile robot inan exemplary architecture suitable for implementing the invention;

FIG. 5 is a schematic top view showing attracting beams and repellingbeams in an exemplary embodiment;

FIGS. 6A-E are diagrams illustrating various steps of an exemplaryactivation cycle for the sources of attracting and repelling beams;

FIGS. 7A-E are diagrams illustrating various steps of an exemplaryprocess in the approach and identification of a mobile robot to thedocking station;

FIGS. 8 and 9 are flowcharts illustrating steps implemented respectivelyby a mobile robot and a docking station according to an exemplary methodfor recharging the battery of the robot;

FIG. 10 is a diagram illustrating a mobile robot calibration procedureusing the docking station; and

FIG. 11 is a diagram showing an exemplary communication architecturesuitable for implementing the invention.

DESCRIPTION OF EMBODIMENTS

The docking station 10 shown by way of example in FIGS. 1 and 2 rests onthe ground by means of a plate-shaped base 11 which defines a parkingarea for a mobile robot 20. It further comprises a housing 12 whichcontains a number of components described below, and a pillar 13 at theback of the station relative to the robot parking area.

In this example, the docking station 10 is designed to be placed in acorner of a room. The rear side of the housing 11 and pillar 12 form aright-angle that can be fit into the corner, and the structure of thedocking station is generally symmetrical relative to the bisector of theright angle. A connector is provided at the rear of the housing 12, witha plug 14 to supply electricity to the station 15 and a network port.

The front of the housing 12 has a concave profile to enable receiving amobile robot 20 having a generally circular base within the parkingarea. The opening in the front of the housing may be designed toaccommodate robots 20 of different diameters or shapes in the parkingarea.

In the front of the housing 12, the base 11 has two contactors 16 whichcooperate with charging contacts located on the underside of the mobilerobots 20. The contactors 16 are connected to electric components housedin the housing 12.

Sources of guide beams, typically infrared LEDs 21-25, are placed on thefront of the housing 12 to assist the robot 20 when it approaches thestation 10. An infrared transceiver 26 is also provided to allowshort-range communication between the docking station 10 and a robot 20which is docked.

FIG. 3 illustrates the electronic components that can be found insidethe docking station 10. Of course, the illustrated architecture, whichis organized around a bus 30, is a simple non-limiting example. In thisexample, the bus 30 is controlled by a processor 31 accommodated in thehousing 12, which supervises the operation of the various components bymeans of appropriate software modules. Here these components include:

-   -   a memory 45 associated with the processor 31;    -   a network interface 32, for example Ethernet, coupled with an IP        router, which enables connecting the docking station 10 to the        network of a company using a fleet of mobile robots, and/or to        the Internet, via the network port 15;    -   a WiFi access point 33 providing a wireless communication        interface with the mobile robots operating in the environment        where the docking station is installed;    -   an infrared communication interface 34, for example IrDA;    -   a controller 35 for the infrared LEDs 21-25;    -   an omnidirectional source, such as an infrared LED 36, which        emits a beacon signal at or near the docking station 10;    -   a sensor 37 for detecting the presence of a robot docked in the        docking station, which cooperates with the exposed contactors 16        in the parking area;    -   a recharging controller 38 which oversees the process of        recharging the mobile robots;    -   a component 39 which collects the measurements made by a set of        reference sensors 40 equipping the docking station 10.

Note that some of the components 32-39 shown separately in FIG. 3 maypossibly be implemented, in all or part of their functionality, assoftware modules executed by the processor 31 or one of its devices.

FIG. 4 illustrates electronic components that may be found inside arobot 20. Of course, the specified architecture, which is organizedaround a bus 70, is a simple non-limiting example. In this example, thebus 70 is controlled by a controller 71, such as a microprocessor ormicrocontroller, embedded in the robot 20, which oversees the operationof the various components by means of appropriate software modules.These components include here:

-   -   a memory 85 associated with the controller 71;    -   a WiFi terminal 73 for wireless communication with the access        point 33 of a docking station 10, or with another WiFi access        point;    -   an infrared communication interface 34, for example IrDA, for        short-range communication with the infrared interface 34 of a        docking station 10;    -   a motor system 78 comprising one or more motors arranged to move        the robot 20 autonomously with power supplied from the battery        75 of the robot;    -   a plurality of infrared sensors 76 for detecting the guide beams        emitted by the sources 21-25 of a docking station 10 and the        beacon signal emitted by the source 36 of such a station;    -   a switch 81 which, when so instructed by the controller 71,        presents the voltage 75 from the battery to a pair of charging        contacts 28 which are accessible from outside the robot, for        example under its chassis, for recharging the battery 75; and    -   a component 79 which collects the measurements made by a set of        sensors 80 on board the robot 20.

One will also note that some of the components 73, 74, 79, 81 shownseparately in FIG. 4 may possibly be implemented, in all or part oftheir functionality, as software modules executed by the controller 71or one of its peripherals.

FIG. 5 shows an exemplary geometry of the attracting and repelling beamsemitted by the infrared LEDs 21-25 of the docking station 10.

LED 21 emits an attracting beam R1 oriented in the horizontal directionX1 and passing through the plane of symmetry of the docking station 10.

LEDs 22, 23, arranged at the sides of the front face of the housing 12,emit respective attracting beams R2, R3 in directions X2, X3 arrangedsymmetrically relative to direction X1. Directions X1, X2 and X3intersect at a point P located within the parking area of the dockingstation. In the example shown, the angle formed between directions X1,X2 and between directions X1, X3 is about 50°.

Infrared LEDs 24, 25 are arranged laterally on the front face of thedocking station 10, near the corners thereof. They emit repelling beamsR4, R5 of shorter range than the attracting beams R1, R2, R3 (forexample 15 to 30 cm compared to 50 to 100 cm). As shown in FIG. 5, thebeamwidth of the repelling beams R4, R5 is preferably greater than thatof the attracting beams R1, R2, R3 (for example about 60° compared to15°). The angle formed between directions X1, X4 and between directionsX1, X5 is for example from 10 to 20°.

When it needs to return to the docking station 10 in order to charge itsbattery 75 or for other services, a mobile robot 20 can no longer relyon its obstacle avoidance systems to determine its path. Otherwise itwould never reach the docking position at the docking station, which isthe position where its charging contacts 28 on its underside are againstthe contactors 16. The robot must therefore be guided from the outside,which is the role of the infrared sources 21-25.

The mobile robots 20 are equipped with infrared sensors 76 at the heightof the LEDs 21-25. When one of the attracting beams R1-R3 is sensed by amobile robot, the controller 71 determines the direction of origin ofthe beam and controls the motor system 78 so that the robot movestowards the LED from which the beam was emitted. In contrast, if it is arepelling beam R4, R5, the motor system 78 is controlled so that therobot moves away from the LED where it originated. The distinctionbetween attracting and repelling beams is made by the robot 20 byreceiving the beacon signal emitted by the LED 36 of the docking station10, the beams being emitted sequentially according to an activationcycle controlled by the controller 35.

The LEDs 21-25 are successively activated by the controller 35 in acycle whose frequency is for example 20 Hz. The activation cycle iscomposed of several steps during which the LEDs 21-25 are activated inturns. At the same time, a specific encoded signal is emitted by thebeacon LED 36. This activation cycle guides the robot 20 to the station10 while managing priorities between the beams, measuring the ambientinfrared noise and having the robot identify the station.

The LED beacon 36 thus emits omnidirectional infrared signal packetshaving a header which includes an identifier of the docking station 10,and a packet body which provides codes indicating the current steps ofthe activation cycle. There are for example five steps of the sameduration in the activation cycle, illustrated by FIGS. 6A-E:

-   -   a first step (FIG. 6A) in which none of the LEDs 21-25 is        supplied power, the docking station being able to measure the        ambient infrared noise by means of an infrared sensor 41        associated with the controller 35 (FIG. 3);    -   a second step (FIG. 6B) in which only LEDs 24, 25 are activated        to emit repelling beams R4, R5;    -   a third step (FIG. 6C) in which only LED 22 is activated to emit        attracting beam R2;    -   a fourth step (FIG. 6D) in which only the opposite LED 23 is        activated to emit attracting beam R3; and    -   a fifth step (FIG. 6E) in which only the central LED 21 is        activated to emit attracting beam RE

When a robot detects one of the infrared beams R1-R5 in the vicinity ofthe docking station 10, it reads the code transmitted in the beaconsignal to determine which beam is concerned. It can then orient itselfand move towards the parking area of the docking station. When theactivation cycle is in the first step (FIG. 6A), the robot can alsomeasure the ambient infrared noise using its sensors 76.

While being guided, the robot (at least its infrared receiver) drawsnear to the intersection point P of beams R1-R3 (FIG. 5). The ambiguityconcerning the direction the robot must follow to complete the dockingprocedure is removed by means of codes transmitted by the LED beacon:the robot is programmed to head towards the source 21 of beam R1detected during the fifth step of the cycle illustrated in FIGS. 6A-E,which brings it to the docking position. In other words, beam R1 has apriority property which, in the example considered here, is expressed inthe codes emitted by the LED beacon 36.

Measurement of the ambient infrared noise by sensors 41 and/or 76 duringthe first step of the activation cycle allows controller 35 and/or 71 totake into account the signal-to-noise ratio. The higher the measuredambient noise is, the stricter the selected criteria used to separate asignal from the ambient noise is chosen. This method prevents the guidesignals from being altered by environmental disturbances such asvariations in brightness or wave pollution.

Each mobile robot 20 has a predefined list of docking stations withwhich it is allowed to dock, stored in its memory 85. The identifier ofthe docking station 10 which it is approaching, broadcast in the beaconsignal emitted by LED 36, allows the robot to check whether it isauthorized for that docking station.

Alternatively, identification of the docking station 10 by a mobilerobot 20 can be performed using the association identifier broadcast onthe IEEE 802.11 beacon channel by the WiFi access point 33 of thestation 10.

It is appropriate for the docking stations 10 also to be able tosecurely identify the robots 20 that come to them.

The robot presence sensor 37 and the infrared communication interface 34may be used for this, according to a procedure illustrated in FIGS.7A-E.

FIG. 7A shows a mobile robot 20 which is approaching a docking station10. The detection of a guide signal from a station authorized for agiven robot, meaning one of beams R1-R3 and the beacon signal emitted bythe LED 36, allows the robot to verify that the station is indeedauthorized and then to present the voltage from the battery to thecharging contacts 28 located under its chassis (FIG. 7B). Thus, once arobot is properly positioned in a station (FIG. 7C), the station detectsit by reading on its contactors 16 the residual voltage from the batteryof the robot. This is the role of the robot presence sensor 37 coupledto the contactors 16.

In order to have a secure procedure to initiate charging, the station 10then begins a dialog with the robot 20 via infrared communication. Thestation 10 first checks that the voltage it detects is indeed thevoltage of the robot. For this purpose, the station 10 requests therobot 20 to identify itself, via the infrared interface 34 (FIG. 7D).

If the reply sent by the robot 20 (FIG. 7E) identifies it correctly,meaning if the robot identifier returned appears in a list ofidentifiers authorized for the docking station 10, stored in the memory45 of the station, the station makes available all of its capabilities(charging and other services) to the robot 20. In addition, it recordsthe information that the robot in question is indeed docked at thestation 10, making this information accessible to the robot fleetcontroller via the network interface 32.

If the station 10 does not receive a response or if the robot returns aninvalid or unauthorized identifier (7E), the station does not supplycharge current nor any of the other services it offers.

The method described above, of dual identification of docking stationsby robots and of robots by docking stations, allows simple and flexiblemanagement of the operation of a robot fleet having access to aplurality of docking stations.

The pairing between robots and docking stations, meaning the storage oflists of robots and stations authorized to work together, can be donewhen deploying robots and stations at an operating site. A simple way todo this is to present a robot 20 to a station 10 which it will beauthorized to work with and to activate a coupling procedure by means ofa button provided on the robot or the station, this procedure consistingof registering the identifier of the robot in the memory 45 of thedocking station and that of the docking station in the memory 85 of therobot. Another way to pair consists of providing lists of robots and thestations with which they can connect by means of a computer interfaceavailable to the fleet controller (tablet or computer) and thentransmitting the appropriate lists to the docking stations via theirnetwork interfaces 32, and to the robots via the WiFi network.

Managing the recharging process for high capacity robots advantageouslyincludes a number of measures to ensure greater reliability and bettersafety. It may be that the docking station 10 receives robots 20 havingbatteries of different electrical properties. It must then be providedwith charging circuitry 42 able to deliver different voltage/currentproperties. Due to the identification of the presenting robots, therecharging controller 38 of the station can select the appropriate modeof operation of the recharging circuits 42 for each robot.

As the current involved can be significant, it is critical to have asafe charging process. When the voltage exceeds 5 volts and the currentseveral amperes (for example 25V/7 A or more), the safety constraintsare more strict.

This is why it is appropriate for the recharging controller 38 tocontrol the recharging circuits 42 (transformers, switches, andassociated electronics) so that, by default, the charge voltage is notavailable on the contactors 16 of the docking station 10. Thiseliminates the risk of an accidental short-circuit. The rechargingprocedure entails the robot identifying itself (FIGS. 7D-E) andpresenting the residual voltage from its battery 75 to its chargingcontacts 28. It is under these preconditions that charge power issupplied at the contactors 16 of the station. The battery of the robot20 can then begin recharging.

Managing the approach of the robot for recharging purposes can beperformed according to the procedures illustrated in FIG. 8 concerningthe mobile robot (controller 71) and in FIG. 9 concerning the dockingstation (processor 31 and/or recharging controller 38).

In response to detection of a beacon signal by an infrared sensor 76 ofthe robot (step 90), the controller 71 first checks whether theidentifier of the docking station carried by the beacon signal appearsin the list of authorized stations available in the memory 85 of therobot (test 91). If it is an unauthorized identifier, the controller 71controls the motor system 78 so that the robot 20 moves away from theunsuitable docking station 10 (step 92).

If the identifier received in the beacon signal is that of a dockingstation authorized for the robot, the controller 71 controls the switch81 so that the voltage from the battery 75 is present on the chargingcontacts 28 of the robot (step 93). Then the robot waits to receive arequest for identification from the docking station (test 94). Uponreceipt of this request, the controller 71 controls the infraredinterface 74 so that the identifier of the robot 20 is transmitted tothe docking station 10 in step 95.

After transmitting its identifier, the controller 71 of the robotexamines whether a rejection message is received on the infraredinterface 74 from the docking station 10 (test 96). In case of rejectionby the host station, step 92 is executed so that the robot moves awayfrom the station. If the robot is accepted by the docking station, itstarts to receive the power delivered by the docking station at itscharging contacts 28 in order to recharge its battery 75 (step 97).

As for the docking station 10, the procedure illustrated in FIG. 9 istriggered by the detection 100 of voltage at the contactors 16 placed inthe parking area, by the sensor 37. In response to detecting voltage atthe contactors 16, the processor 31 controls the infrared interface 34so that the request for identification from the robot 20 which hasreached the parking area is transmitted (step 101).

Then the docking station 10 waits to receive a message supplying theidentification of the mobile robot (test 102). Upon receipt of thismessage, the processor 31 verifies (test 103) that the receivedidentifier appears in the list of robots authorized for the dockingstation, stored in memory 45. If it is an unauthorized identifier, theprocessor 31 orders the transmission, by the infrared interface 34, of arejection message for the robot that has reached the parking area. Ifthe mobile robot 20 is authorized for the docking station 10, thestation's processor 31 controls the recharging controller 38 so thatcharge power for the robot battery is sent to the contactors 16.

Once charging the robot battery 75 has been initiated, measurements arecontinuously collected by means of the sensors 43 equipping the dockingstation:

-   -   voltage of the robot battery 75 measured at the terminals of the        contactors 16;    -   charge current amperage; and    -   temperature of the charge circuits.

These measurements, to which can be added the temperature of the robotbattery 75 as measured by the robot and transmitted to the station viathe WiFi or infrared interface (step 98 of FIG. 8), are used to definethe charging status (no robot present, charging initialization,charging, end of charging) but also to define ranges of measurementsdefining normal operation.

The measurements made by the docking station 10 and those received fromthe robot 20 during recharging are analyzed by the processor 31 in step106 represented in FIG. 9. If one of the indicators lies outside thenormal operating range, an alert is triggered by the rechargingcontroller 38. The alert leads the recharging controller 38 toautomatically stop the charge voltage at the contactors 16. One can thusdetect and terminate any malfunction, whether or not it is potentiallydangerous. If an anomaly is detected, a warning message is issued by thedocking station 10 via the Ethernet in order to inform the robot fleetmanager.

Other interesting features of the docking station 10 described here asan example relate to the sensors 80 on board the mobile robots 20. Inparticular, in the application where a set of robots is used to carryout air quality measurements in a closed environment in which thedocking station is also located, the robots have embedded sensors 80measuring quantities such as:

-   -   room temperature;    -   relative humidity;    -   the toxic or undesirable gas content in the ambient air (carbon        dioxide, ozone, volatile organic compounds, etc.);    -   dust, allergens, or other particle content in the ambient air.

As is known, the responses of these sensors 80 are not completely stableover time. It is therefore useful to provide dynamic maintenance tocorrect their drift. Indeed, a robot that can carry numerous sensors,some of which are networked to render the expected service more robust,may see its services decline or generate false data because of drift inits sensors, which will be integrated into the databases.

To detect drift in a given sensor 80, it is necessary to compare thevalue it measures to that provided by a reference sensor which is nextto it. Traditionally, this involves either a technician visit to therobot deployment site, or sending the robot or its sensor to anothertest site.

In the context of a network of sensors 80 on board mobile robots, thisproblem can be alleviated by the presence of reference sensors 40 in thedocking station 10 which is presented in this document.

The reference sensors 40 (FIG. 3) may be housed inside the pillar 13 ofthe docking station. In the example shown in FIGS. 1 and 2, air vents44, 45 are provided on the pillar 13, on the front and at the top, sothat the air measured by the sensors 40 of the docking station 10 isshared with the air measured by the sensors 80 equipping a docked robot20.

Since all the robots 20 regularly come to a docking station to recharge,they spend a fair amount of time there, allowing enough sampling forcomparing data from the onboard sensors 80 and the reference sensors 40.Calculation of drift correction factors and failure detection areperformed for each robot which comes to recharge. The maintenanceoperation consisting of verifying the sensors 80 on board the robots maybe done exclusively by means of sensors of the docking station 10.

Sensor maintenance may for example be performed as follows. The data(raw data and corrected data) measured by the docking station 10 and bythe robots 20 are sent to a collection server 50 via the networkinterface 32 (FIG. 10: step 51). The measured data are analyzed by theserver 50 in order to calculate the correction parameters.

The correction calculation for a given sensor 80 of a robot 20, whichcorresponds to a reference sensor 40 of a docking station 10, maycomprise:

-   -   comparing the data measured by the robot 20 located in a docking        station 10 (detection by presence of the robot in the station);    -   using the value measured by the sensor 40 of the station 10 as a        reference;    -   estimating the correction from the differences between the        measurements made by the docked robot and those made by the        station. Depending on the type of sensor, regression which is        linear (for example by least squares), polynomial, or other, is        applied to the data to define the correction parameters;    -   if the drift represented by the correction parameters is too        large, an on-site maintenance operation may possibly be decided        upon for the sensors 40 of the docking station 80 or for those        of a robot (FIG. 10: step S2);    -   transmitting the correction parameters to the docking station 10        via the network interface 32 (FIG. 10: step S3) and, from there,        to the robots 20 via the WiFi access point 33.

One interesting possibility is to perform a counter-assessment ofmeasurements from the reference sensors 40, using measurements made bysensors of the same type 80 on board a population of robots, applyingthe principle: “the majority can challenge the reference.” In this case,the measurements of the robot sensors 80 are expressed as deviationsfrom the reference measurement from a sensor 40 of the docking station.These deviations given for the different robots of the population arecompared. If a majority of the robots confirms a deviation in the samedirection, the reference sensor 40 is called into question, and an alertis triggered to the fleet manager so he can decide on a maintenanceoperation on the reference sensor 40 of the docking station orrevalidating the calibration of the reference sensors 40 if this hasbeen done recently.

Making use of the data from the reference sensors 40 equipping thedocking station 10 can greatly reduce the need for on-site maintenancefor robots 20.

In the context of using a fleet of robots to measure air quality, thedata measured by the embedded sensors 80 are continuously sent to thecollection server 50 via the WiFi access point 33 of a docking station10 and its network interface 32 (indicated by arrows 51, 52 in FIG. 11).If necessary, the collection server 50 returns correction parameters tothe robots, as has just been described.

The network interface 32 further enables communication with a softwareupdate server 60 (FIG. 10) which may be distinct from the collectionserver 50. When new versions of the robot firmware are developed, theycan be downloaded from the update server 60 to the robot 20 via thenetwork interface 32 of the docking station 10 (arrow 53) and its WiFiaccess point 33 (arrow 54).

On the basis of the features offered by the docking station 10, theproposed architecture again facilitates maintenance, this time of thefirmware, of the robot fleet.

The embodiments described above are merely an illustration of thepresent invention. Various modifications can be made without departingfrom the scope of the invention as defined in the accompanying claims.

Although the electric power delivery interface equipping a dockingstation has been described as consisting of a pair of contactors 16,while the electric power receiving interface of a robot has beendescribed as consisting of a pair of charging contacts 28, this is notthe only type of power interface that can be used. Induction charging isalso possible, for example.

Also note that the technical elements described above concerning themethod for guiding the robot to the docking station, the mutualidentification of docking stations and robots, the secure management ofrobot recharging, the communication architecture for robots/dockingstation/server(s), the procedures for calibrating robot sensors and forupdating their firmware, can be implemented independently of oneanother, although their combination can offer robot users particularlyeffective docking stations, well suited for the deployment of sizablefleets of robots offering a variety of services.

The invention claimed is:
 1. A system for monitoring air quality in atleast one environment, comprising: at least one mobile robot in theenvironment; a docking station placed in the environment and having aparking area for receiving the robot; air quality sensors on board themobile robot; air quality sensors installed in the docking station; anda calibration controller for collecting measurements made by at least afirst air quality sensor on board the mobile robot, while the mobilerobot is received in the parking area of the docking station, and forcollecting measurements made at the same time by a second air qualitysensor installed in the docking station and of the same type as saidfirst air quality sensor.
 2. The system of claim 1, wherein thecalibration controller is configured to transmit to the mobile robotdrift observed in the collected measurements correction parameters. 3.The system of claim 1, wherein the calibration controller is installedat least in part in the docking station, the system further comprising acollection server communicating with the calibration controller toprocess the collected measurements and to provide drift observed in thecollected measurements correction parameters.
 4. The system of claim 3,wherein the drift observed in the collected measurements correctionparameters are determined by the collection server in order to calibratethe first air quality sensor on board the mobile robot relative to thesecond air quality sensor installed in the docking station.
 5. Thesystem of claim 3, wherein the docking station is able to successivelyreceive a plurality of mobile robots in the parking area, wherein thecollection server is configured to process measurements made by firstair quality sensors of the same type on board their respective mobilerobots while said mobile robots are successively received in the parkingarea, in comparison to measurements made at the same time by the secondair quality sensor installed in the docking station and of the same typeas said first air quality sensors.
 6. The system of claim 5, wherein theprocessing of measurements by the collection server includes an analysisof the differences observed between the measurements made by the firstair quality sensors and those made at the same time by the second airquality sensor, and triggering an alert when the analyzed differencesmeet a predefined alert condition.
 7. The system of claim 3, wherein thecollection server is configured to communicate with calibrationcontrollers installed at least in part in a plurality of dockingstations.
 8. A mobile robot docking station comprising: a parking areafor receiving at least one mobile robot in an environment where thedocking station is placed; reference sensors of the same type as the airquality sensors on board a mobile robot; and a calibration controller tocollect air quality measurements made by at least one air quality sensoron board a mobile robot while said mobile robot is received in theparking area, and measurements made at the same time by a referencesensor of the docking station.
 9. The docking station of claim 8,further comprising a network interface for transmitting data obtained bythe mobile robot to a collection server, the calibration controllerbeing configured to transmit to the collection server, via the networkinterface, the air quality measurements made by the air quality sensoron board the mobile robot while said mobile robot is received in theparking area, and the measurements made at the same time by a referencesensor of the docking station.
 10. The docking station claim 8, whereinthe calibration controller is configured to transmit to the mobile robotdrift observed in the collected measurements correction parameters. 11.The system of claim 4, wherein the docking station is able tosuccessively receive a plurality of mobile robots in the parking area,wherein the collection server is configured to process measurements madeby first air quality sensors of the same type on board their respectivemobile robots while said mobile robots are successively received in theparking area, in comparison to measurements made at the same time by thesecond air quality sensor installed in the docking station and of thesame type as said first air quality sensors.
 12. The system of claim 4,wherein the collection server is configured to communicate withcalibration controllers installed at least in part in a plurality ofdocking stations.
 13. The system of claim 5, wherein the collectionserver is configured to communicate with calibration controllersinstalled at least in part in a plurality of docking stations.
 14. Thesystem of claim 6, wherein the collection server is configured tocommunicate with calibration controllers installed at least in part in aplurality of docking stations.
 15. The docking station claim 9, whereinthe calibration controller is configured to transmit to the mobile robotdrift observed in the collected measurements correction parameters. 16.The system of claim 11, wherein the collection server is configured tocommunicate with calibration controllers installed at least in part in aplurality of docking stations.